buttercup vs sugar baby

buttercup

noun
  • Affectionate or ironic term of address. 

  • Any of many herbs, of the genus Ranunculus, having yellow flowers; the crowfoot. 

  • Any flower of the genus Narcissus; a daffodil. 

sugar baby

noun
  • A term of endearment; sweetheart. 

  • The younger recipient (usually female or a bottom) of interest from a sugar daddy or sugar mama, especially financial and romantic in an intergenerational relationship 

How often have the words buttercup and sugar baby occurred in a corpus of books? (source: Google Ngram Viewer )